GABA-ACTIVATED AND GLUTAMATE-ACTIVATED CURRENTS IN GLIAL-CELLS OF THE MOUSE CORPUS-CALLOSUM SLICE

Whole-cell transmitter-activated currents were recorded with the patch-clamp technique from glial cells in thin frontal brain slices of the corpus callosum. In slices from 6- to 8-day-old mice, glioblasts were predominantly found, while oligodendrocytes were predominant in slices from 10- to 13-day-old mice. These developmental stages could be readily distinguished by their K+ channel pattern and their morphology and ultrastructural features. Both cell types expressed GABA and glutamate receptors in this in situ preparation. GABA responses showed similarities to those described for GABA(A) receptors, i.e., they were mimicked by muscimol, blocked by bicuculline, and enhanced by pentobarbital. Glutamate responses showed similarities to those of the kainate/quisqualate receptor subtype. The amplitude of GABA-activated currents recorded in oligodendrocytes was significantly smaller than that from glioblasts, while glutamate responses did not show marked differences in either cell type.